1. Field of the Invention
The present invention relates to a holder for a spot welder tip dresser, and more particularly, to a holder for a spot welder tip dresser with an adjustable cutting rate, which functions to center a spot welder tip of a spot welding robot and adjust the protruding length of a cutter so as to enable adjustment of a cutting rate of the tip.
2. Description of the Related Art
A spot welder, which is generally used to weld vehicle panels, etc., is a resistance welder in which upper and lower electrode tips are positioned to press both surfaces of metal panels and apply electric current thereto so as to weld them. There broadly exist two kinds of spot welders depending on pressure mechanisms.
The two kinds of spot welders include an air gun which employs a pneumatic cylinder as a pressure drive source, and a servo gun which employs a servo motor as a pressure drive source.
Although the air gun has mainly been used, the air gun is currently being replaced by the servo gun for the purpose of improving welding quality because the servo gun is capable of more precisely adjusting pressure. To improve welding quality, moreover, it is important to periodically cut an electrode tip of a welder by an appropriate degree so as to form and maintain even nuggets (welding spots) of the electrode tip.
Here, factors determining cutting rate per revolution of a tip dresser include the protruding length of a cutter from a guide surface of a holder and pressure of a welding gun during dressing of the tip.
Korean Registered Utility Model No. 0439234 discloses a conventional holder for a tip dresser in which a cutter 120 is closely secured to a partition 113 so as to protrude by a predetermined height. More particularly, if dressing pressure of a welding gun exceeds a preset pressure, the welding gun may push a tip beyond the preset pressure, causing excessive cutting of the tip. This disadvantageously causes frequent replacement of the tip due to an excessive cutting rate of the tip. On the other hand, if the dressing pressure of the welding gun is lower than the preset pressure, the welding gun may exert a force insufficient to correctly cut the tip and consequently, cause formation of uneven nuggets at the tip.
This may disadvantageously deteriorate welding quality or consume excessively long time for cutting the tip. As a result, time delay due to frequent replacement of tips or relatively long cutting time results in increased overall welding time and maintenance costs.